The separation of carbon dioxide (CO2) from a mixed-gas source may be accomplished by a capture and regeneration process. More specifically, the process generally includes a selective capture of CO2, by, for example, contacting a mixed-gas source with a solid or liquid adsorber/absorber followed by a generation or desorption of CO2 from the adsorber/absorber. One technique describes the use of bipolar membrane electrodialysis for CO2 extraction/removal from potassium carbonate and bicarbonate solutions.
For capture/regeneration systems, a volume of gas that is processed is generally inversely related to a concentration of CO2 in the mixed-gas source, adding significant challenges to the separation of CO2 from dilute sources such as the atmosphere. CO2 in the atmosphere, however, establishes equilibrium with the total dissolved inorganic carbon in the oceans, which is largely in the form of bicarbonate ions (HCO3−) at an ocean pH of 8.1-8.3. Therefore, a method for extracting CO2 from the oceans would effectively enable the separation of CO2 from atmosphere without the need to process large volumes of air.